code: def test_union(self, container, lst):
      result = container.union((1, 2, 3))
      expected = FrozenList(lst + [1, 2, 3])
      self.check_result(result, expected)
  
file_path: pandas/pandas/tests/indexes/test_frozen.py
imports: import re
  import pytest
  from pandas.core.indexes.frozen import FrozenList
label_desc: Use image node_id 9 for calling the TestFrozenList obj's underlying member method code with example usage: obj.test_union(container, lst) without return types